This invention relates generally to a composition for controlling the release of biologically active compounds. In particular, this invention relates to the use of certain polyphenolic compounds to control the release of biologically active compounds.
The ability to control release of biologically active compounds to a locus to be protected is important in the field of biologically active compounds. Typically, when a biologically active compound is added to a locus to be protected, the compound is rapidly released, whether or not it is needed. Controlled release compositions deliver the biologically active compound in a manner that more closely matches the need for the compound. In this way, only the amount of the biologically active compound needed is released into the locus to be protected. Controlled release offers the advantages of reduced cost, lowered toxicity and increased efficiency.
Various methods of controlled release are known. Such methods include encapsulation of the biologically active compound, adsorption of the biologically active compound on an inert carrier, such as silica gel, and clathration of the biologically active compound.
All of these methods have drawbacks to widespread commercial use, such as expensive starting materials, limited compatibility of the controlled release method to the compounds to be released or locus to be protected, and limited control of the release of the biologically active compounds. For example, whether a clathrate forms is solvent dependent, which limits available solvent choices. An additional problem with clathrates is that solvent, rather than the desired biologically active compound, is sometimes incorporated into the complex.
For example, EP 709 358 A (Suzuki et al.) discloses a clathrate of isothiazolones using a tetrakisphenol compound. Although these compositions provide some control of the release of the isothiazolone, the amount of control is limited and the tetrakisphenol compound used to prepare the clathrate is very expensive. Suzuki et al. do not discuss polyphenolic compounds other than tetrakisphenols.
JP 07 003 191 A, assigned to Kurita, discloses a clathrate of isothiazolones with 5,5'-dichloro-2,2'-dihydroxydiphenylmethane for use in marine antifouling paints. These compositions have achieved limited success because 5,5'-dichloro-2,2'-dihydroxydiphenylmethane is banned in some countries.
There is therefore a continuing need for controlled release biologically active compositions that are inexpensive, compatible in a broad range of loci to be protected, and more effective at controlling the release of the biologically active compound than compositions currently available.